JPH0790765B2 - Failure detection circuit for anti-lock brake device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to anti-lock braking systems, and in particular fault detection for sensing, analyzing and generating signals to control the operation of anti-lock braking systems in response to detected faults in the system. It is about circuits.

Antilock braking devices are well known. Early anti-lock braking systems were of substantially mechanical construction. This type of anti-lock braking system is now improved as a complex device that can control the application of braking force quickly and accurately to significantly improve brake actuation control under changing driving and road conditions. Has been done. The strong demand for safety and performance in addition to the proven effectiveness of this type of device has made it urgent to disseminate this type of device.

Antilock braking devices typically include a master cylinder having a main cylinder or chamber and a secondary cylinder or chamber, and a power booster device having a pump and accumulator for producing pressurized braking fluid. An electronic controller issues a brake pressure control signal in response to predetermined vehicle operating parameters such as wheel speed, wheel acceleration, and the like. A regulator valve device controls the brake pressure level in response to the control signal to provide optimum braking on the wheels of the vehicle. As an example of this type of device, U.S. Pat. A structure of a regulating valve device for an antilock brake device, which is configured to be connected to a main chamber and a sub chamber of a master cylinder, is disclosed. The normally closed pressure generating valve and the normally closed pressure reducing valve have a common fluid connection which is connected to the wheel cylinder via a corresponding shutoff valve.

This type of antilock brake system is quite expensive.
Therefore, there is a long-felt need to reduce the complexity and cost of such devices while maintaining a high level of operational reliability and safety. Even extremely precise parts can fail as a result of wear, abuse or damage. Therefore, a failure of a component is detected and analyzed, the operation of the braking device is controlled so as to have the maximum braking operation that can be used in the event of a failure, and the braking device and the driver are warned of the occurrence of this failure. It is desired to equip the antilock brake device with a device that can inform the type of failure.

From British Patent No. 2,162,265 it is known to use a single differential pressure switch in an adaptive braking system (ie an antilock braking system) which measures the differential pressure between a main fluid circuit and a secondary fluid circuit. However, providing only one differential pressure switch is not sufficient to confirm various failure modes in the antilock brake device.

Accordingly, it is an object of the present invention to detect and analyze operating parameters of an anti-lock braking system and to generate a plurality of output signals for controlling the operation of the anti-lock braking system based on a detected fault in the system. A fault detection circuit for an anti-lock braking system comprising a fluid level switch, a pressure responsive switch and a network of logic circuits connected to the.

To this end, the present invention provides a master cylinder having a main cylinder and a sub cylinder and a boost cylinder connected to a main fluid circuit and a sub fluid circuit, respectively, including at least one wheel cylinder, a pump, an accumulator and a pressurizer. A fluid booster device including a manually adjusted valve for selectively supplying brake fluid to the master cylinder, and an anti-swing device that senses a rotational speed of a vehicle wheel braked by the wheel cylinder and issues a plurality of brake control signals. A lock control system, wherein the antilock control system further includes an antilock regulating valve device that cooperates with the wheel cylinder to regulate communication of brake pressure to the wheel cylinder in response to the brake control signal. In the anti-lock brake device, the main fluid circuit and the sub fluid A differential pressure switch operating in response to two different differential pressures between a channel and the boost cylinder, the first differential pressure switch between the auxiliary fluid circuit and one of the boost cylinder and the main fluid circuit. A second differential pressure switch connected to one of the sub-fluid circuit and the main fluid circuit to actuate from a normal state to an operating state to generate a first differential pressure signal in response to a predetermined differential pressure therebetween. Two differential pressure switches connected to the boost cylinder and actuated from a normal state to an activated state to generate a second differential pressure signal in response to a predetermined differential pressure therebetween; and the fluid booster. A low pressure switch which is connected to the device and which operates in response to a predetermined minimum pressure to generate a low pressure signal, wherein the arithmetic circuit of the antilock control system comprises the first and second differential pressure switches and the low pressure switch. output In response, a fault for an anti-lock braking device characterized by activating or deactivating the anti-lock control system as a function of the logical combination of the outputs of the first and second differential pressure switches and the low-voltage switch. It provides a detection circuit.

According to this configuration, the arithmetic circuit of the antilock control system analyzes the logical combination of the outputs of the first and second differential pressure switches and the low pressure switch, so that various failures of the antilock brake device, for example, pump failure, Faults such as gas mixture in the brake line and fluid leakage can be detected, and the anti-lock control system can be activated or deactivated depending on the detected fault. Two differential pressure switches and a low pressure switch The reliability of the fault detection circuit can be increased by only requiring a minimum number of pressure switches.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the drawings, FIG. 1 shows a functional block circuit diagram of an antilock brake device or an adaptive brake device used in a vehicle such as an automobile. The anti-lock brake system includes a dual-sliding master cylinder full power booster system 10 having a main cylinder or chamber 12 and a secondary cylinder or chamber 14 which are each actuated by a pressurized fluid in a boost cylinder or chamber 16. . The pressure of the fluid in the boost chamber 16 is manually adjusted by a foot pedal 18 operatively connected to a pressure control valve 20. Pressurized fluid for the braking system is supplied from motor driven pump 22 and accumulator 24 via fluid line 26. Fluid is supplied from fluid reservoir 28 via line 30 to pump 22. The fluid used by the braking device during antilock operation is returned to reservoir 28 via return line 31.

The fluid flows from the reservoir 28 to the fluid lines 32 and 34 and the shutoff valves 36 and 38.
Through the chambers 12 and 14 of the master cylinder. First
Alternatively, the main fluid brake circuit 13 is connected to the chamber 12 and includes an anti-lock regulating valve device 50 connected to one or more wheel cylinders 52. Similarly, the second or secondary fluid brake circuit 15
Includes an anti-lock regulating valve device 56 connected to the wheel cylinder 54.

Regulator valves 50 and 56 are connected in response to control signals from antilock controller 90. The antilock controller 90 receives a plurality of wheel speeds or speed related signals from sensors 58 mounted on the wheels of the vehicle (not shown). The anti-lock controller 90 analyzes the signal from the sensor 58 to determine the impending wheel lock condition and, in response, automatically issues an output signal to control the brake pressure via the regulating valve devices 50, 56. Includes arithmetic circuitry programmed to adjust to prevent wheel locks and maintain vehicle braking at an optimal level.

The regulator valve device 50,56 may be a plurality of solenoid operated valves, such as those disclosed in the applicant's U.S. Patent Application No. 789,203, or U.S. Patent Application No.
A multifunctional device such as that disclosed in 771,550 may be included.

There are also a plurality of switches responsive to the operating parameters of the braking device. These switches are, for example, a fluid level switch 60 operated by a float 61 disposed in the reservoir 28 of the master cylinder to sense a brake fluid level 63, and a first fluid level switch 60 connected between the main chamber 12 and the sub chamber 14. Differential pressure switch 64, main chamber 12 and boost chamber 16
It includes a second differential pressure switch 62 coupled therebetween and responsive to a predetermined differential pressure therebetween, and a pressure sensitive or low pressure switch 66 responsive to a predetermined minimum pressure in accumulator 24.

Switches 60, 62, 64, 66 are connected by conductors 92 to the appropriate inputs of microprocessor-based antilock controller 90. The anti-lock controller 90 is connected to the sensor 58 to sense the wheel speed of the vehicle and to compute a number of parameters of the wheel's rotational movement during braking to produce a plurality of output signals. These signals actuate a plurality of regulator valves 50, 56 to regulate brake pressure.

The anti-lock controller 90 also includes switches 60, 62, 64, 66.
There is suitable software for monitoring the operating conditions of the switches and for issuing appropriate output signals at terminal 94 in response to the logical combination of the operating conditions of these switches. The possible logical combinations of switch operating states are the switch operating states,
The indicated brake system failure conditions and the anti-lock braking system (ABS) control response conditions for each are shown in Table I below.

FIG. 2 is a flow chart showing the logical sequence performed in the microprocessor based antilock controller 90. The particular software for accomplishing this flowchart will, of course, depend on the particular microprocessor or computer used in the antilock brake system. In actual example, anti-lock control device
The 90 incorporates an Intel 8096 type microprocessor.
The output appearing at terminal 94 may be used to visually indicate the operational status of the antilock brake system, or it may activate or deactivate the antilock brake system in response to a number of failure modes. Adjusting valve device 5
It may be applied directly to 0,56 or to the microprocessor itself.

In Table I above, the logical code "1" represents the ON state of the switch to which a signal is issued by the corresponding switch, and the logical code "0" represents the OFF state of the switch. As can be seen from this table, many switches 60-66
It is possible to detect failure of the assembly of the accumulator 24, loss of brake fluid, gas entrainment in the brake circuit and power failure and to determine which of the two brake circuits is defective.

For example, when the brake fluid level 63 in the reservoir 28 is low, the fluid level switch 60 is turned on and outputs an output signal. When such a low fluid level condition occurs, the anti-lock braking device becomes ineffective because the brake circuit does not have enough fluid to be replenished after the depressurization cycle during anti-lock operation. The lock brake device is turned off.

The low-pressure switch 66 measures the pressure in the accumulator 24 on the pump outlet side, and when the pump 22 fails or leaks, responds to the minimum pressure and is turned on to generate an output signal. The failure of this pump / accumulator will cause a shortage of the pressurized fluid necessary to continue the operation of the antilock brake device, so the antilock brake device will be turned off.
It is said that.

When there is a differential pressure between the main chamber 12 and the boost chamber 16, the differential pressure switch 62 is turned on and outputs an output signal. However, when the pressure in the main chamber 12 is low, the differential pressure switch 64 that responds to the differential pressure between the main chamber 12 and the sub chamber 14 also turns on and outputs an output signal, so only the differential pressure switch 62 When the output signal is issued, it can be determined that the booster has failed due to the loss of pressure in the boost chamber 16, and the antilock brake device is turned off.

As described above, when both differential pressure switches 62 and 64 generate an output signal, it is determined that the pressure in the main chamber 12, that is, the main brake circuit 13 is low. Therefore, when only the differential pressure switch 64 outputs an output signal, It can be determined that the pressure in the sub chamber 14 or the sub brake circuit 15 is low. If the main or sub-brake circuit becomes contaminated with gas, the corresponding circuit will generate a low pressure as a result of the compression of the gas in this circuit. Leakage or breakage in either brake circuit will also result in loss of pressure. During the antilock operation, the brake fluid is supplied to the appropriate regulating valve device 5
It exits the brake circuit via 0,56 and normally returns to the reservoir 28. By the circulation of the fluid, the gas mixture state will be automatically corrected in the end. However, brake circuit leakage generally continues with a gradual depletion of brake fluid, ultimately indicating a low fluid level. In either case, the antilock brake device is turned on because the maximum braking performance is exhibited by continuing to operate the antilock brake device until the gas mixture state is eliminated or the low fluid level state is detected. Is done.

Thus, one or both brake circuits will continue to operate in manual mode or power mode depending on whether one of the brake circuits or the pump accumulator is defective. It is impossible to distinguish all possible failures. For example, a brake circuit containing gas gives the same failure indication as a circuit leak. However, such a distinction is not necessary, as the consequences of the braking system resulting from these failures are essentially the same. However, the information provided activates or deactivates the brake system so as to minimize the effects of failure of the antilock brake system during braking of the vehicle. It will be the information necessary for. This operation is accomplished using the minimal pressure sensitive switch, fluid level switch and microprocessor based antilock controller of the antilock brake system.

Tables II and III below relate to variations of the arrangement of the two differential pressure switches 62, 64 shown in Figures 1A and 1B, respectively. As can be seen from the data in this table, each configuration has the data necessary to deactivate the antilock braking system (ABS) in failure mode.

In the above description it is assumed that two failures do not occur at the same time. In addition, all switches incorporate single-acting switches.

While the preferred embodiment of the invention has been illustrated and described, the invention is not limited thereto and can be practiced by those skilled in the art with numerous modifications and / or changes without departing from the scope of the invention. It is clear that this can be done.

[Brief description of drawings]

FIG. 1 is a block circuit diagram of an antilock brake device equipped with a failure detection circuit according to the present invention, FIGS. 1A and 1B are main block circuit diagrams showing modified examples of the present invention, and FIG. 2 is the present invention. 4 is a flow chart showing the logical sequence used to analyze the operation of multiple switches of FIG. 10 …… Master cylinder / Full power booster device, 12
...... Main cylinder or chamber, 13 ...... Main fluid brake circuit, 14
...... Sub cylinder or chamber, 15 …… Sub fluid brake circuit, 16
... Boost cylinder or chamber, 20 ... Pressure control valve, 22 ...
… Motor driven pump, 24 …… Accumulator, 28 …… Fluid reservoir, 50,56 …… Anti-lock adjusting valve device, 52,54
...... Wheel cylinder, 58 …… Sensor, 60 …… Fluid level switch, 62,62 ′, 62 ″ …… Second differential pressure switch, 64,6
4 ', 64 "... 1st differential pressure switch, 66 ... Pressure sensing or low pressure switch, 90 ... Antilock control device.

Claims (1)

[Claims] 1. At least one wheel cylinder (52,5)
Master cylinder (10) having a main cylinder (12), a sub-cylinder (14) and a boost cylinder (16) connected to a main fluid circuit (13) and a sub-fluid circuit (15) including 4), respectively.
And a fluid booster device including a pump (22), an accumulator (24) and a manually adjusted valve (20) for selectively supplying pressurized brake fluid to the master cylinder (10), and the wheel cylinder ( 52, 54) and an antilock control system (58, 90, 94) for detecting a rotational speed of a vehicle wheel to generate a plurality of brake control signals, wherein the antilock control system is the wheel cylinder. An antilock braking device further comprising an antilock regulating valve device (50,56) which cooperates with (52,54) to regulate the communication of brake pressure to the wheel cylinder in response to the brake control signal. Main fluid circuit (13)
And the auxiliary fluid circuit (15) and the boost cylinder (16)
A differential pressure switch that operates in response to two different differential pressures between the auxiliary fluid circuit (15), the boost cylinder (16), and the main fluid circuit. (13) is connected to one of them and is actuated from a normal state to an actuated state in response to a predetermined differential pressure between them to generate a first differential pressure signal, and a second differential pressure switch (62) is The boost cylinder (16) is connected between one of the auxiliary fluid circuit (15) and the main fluid circuit (13) and is actuated from a normal state to an operating state in response to a predetermined differential pressure between them. Two differential pressure switches (64,62) that generate two differential pressure signals
And a low pressure switch (66) connected to the fluid booster device (22, 24) and operating in response to a predetermined minimum pressure to generate a low pressure signal. The arithmetic circuit (90 of the antilock control system is provided. ) Is the first and second differential pressure switch (6
4,62) and the output of the low voltage switch (66) in response to the logical combination of the outputs of the first and second differential pressure switches (64,62) and the low voltage switch (66). A failure detection circuit for an antilock brake device, which activates or deactivates an antilock control system.